The submandibular salivary gland (SSG) synthesizes and secretes growth factors, homeostatic factors and digestive enzymes. This versatility of functional activities provides us with an important model system to study the regulation of normal cell processes and abnormal disease state. This project will study mouse SSG epithelial cell growth and differentiation and how these processes may be altered by functionally distinct viral oncogenes. The experimental approach is based on the use of a culture system that utilizes rat tail collagen as matrix for cell growth. Dissociated SSG epithelial cells from adult mice embedded within the collagen matrix grow and generate 3-dimensional ductal structures by a process reminiscent of tissue morphogenesis. Subculture of the cells in this manner is possible for at least 4 passages. Most importantly, the SSG cells maintain hormonal responsiveness and functional activity, as detected by the accumulation of epidermal growth factor (EGF). The proposed experiments will study SSG progenitor cell behavior in collagen and development of hormonal responsiveness for EGF synthesis. Potential effects of hormones on EGF precursor processing will be analyzed in differentiated cells. The interactions of two viral oncogenes, v-src and v-myc, with functionally differentiated SSG epithelial cells will be examined. Efficient infection of the cells will be accomplished with murine recombinant retroviruses carrying these oncogenes. Potential effects of infection on cellular life-span and properties of normalcy will be established. Quantitative and qualitative aspects of EGF synthesis will be analyzed to establish whether oncogene expression abrogates or alters hormonal requirement or results in the production of aberrant EGF and EGF-related transforming growth factors. These questions are particularly relevant in view of the relationships that exist between retroviral oncogenes and growth factors and their receptors. The proposed studies will provide a better understanding of normal SSG epithelial cell behavior as well as how different viral oncogenes interact with the same epithelial cell environment. Additionally, details on the EGF biosynthetic pathway may help explain the physiological role of EGF in normal cells and in the tumorigenic process.